Dehydration (hypohydration) is defined as an excessive loss of body fluid. It is literally the removal of water (Ancient Greek: ὕδωρ hýdōr) from an object, however in physiological terms, it entails a deficiency of fluid within an organism.
There are three main types of dehydration: hypotonic (primarily a loss of electrolytes, sodium in particular), hypertonic (primarily a loss of water), and isotonic (equal loss of water and electrolytes).[1] In humans, the most commonly seen type of dehydration by far is isotonic (isonatraemic) dehydration which effectively equates with hypovolemia, but distinction of isotonic from hypotonic or hypertonic dehydration may be important when treating people who become dehydrated. Physiologically, it is important to understand that dehydration, despite the name, does not simply mean loss of water, as water and solutes (mainly sodium) are usually lost in roughly equal quantities to how they exist in blood plasma.
Symptoms may include headaches similar to what is experienced during a hangover, muscle cramps, a sudden episode of visual snow, decreased blood pressure (hypotension), and dizziness or fainting when standing up due to orthostatic hypotension. Untreated dehydration generally results in delirium, unconsciousness, swelling of the tongue and, in extreme cases, death.
The treatment for minor dehydration often considered the most effective is drinking water and stopping fluid loss. Plain water restores only the volume of the blood plasma, inhibiting the thirst mechanism before solute levels can be replenished. Solid foods can contribute to fluid loss from vomiting and diarrhea.
souce:wikipedia
